extend function like $.extend

extend.js

function extend(){
  for(var i=1; i<arguments.length; i++)
    for(var key in arguments[i])
      if(arguments[i].hasOwnProperty(key))
        arguments[0][key] = arguments[i][key];
  return arguments[0];
}

For a more complete solution, use: https://github.com/unclechu/node-deep-extend